private static SubtreeInfo Helper(LeetCode333TreeNode root)
{
if (root == null)
{
return(new SubtreeInfo());
}
var left = Helper(root.left);
var right = Helper(root.right);
if (!left.valid || !right.valid || left.max >= root.val || right.min <= root.val)
{
left.valid = false;
left.size = Math.Max(left.size, right.size);
}
else
{
left.valid = true;
left.size = 1 + left.size + right.size;
}
left.min = Math.Min(root.val, Math.Min(left.min, right.min));
right.max = Math.Max(root.val, Math.Max(left.max, right.max));
return(left);
}
public static int LargestBSTSubtree(LeetCode333TreeNode root)
{
return(Helper(root).size);
}
public LeetCode333TreeNode(int val = 0, LeetCode333TreeNode left = null, LeetCode333TreeNode right = null)
{
this.val = val;
this.left = left;
this.right = right;
}